Get thralls on passive and use them to tag every mob there is so you can move them away from thrall you want to knock down. Then you just use trunceon and that’s about it. It takes some practice but that’s the way i do it.
Give your tanks truncheons and your archers blunt arrows. Not sure if it is a bug or working as intended, but my followers have been knocking out thralls very easily since the update. I noticed my concussion bonus was 180% and my follower gets a boost from that. I think they made it way too easy to KO thralls now.